Will not require a magnifying glass and maxi-zoom to read the details. Like a Wikipedia article, a map can be improved by leaving out information/data.

Will be easy to interpret.

While large comprehensive maps have their own encyclopedic uses, they do not work well as a guide to places and other information in the article -- editor will almost always reduce that map's size to the point where it requires the visitor to click to another screen just to read it. But then the map is divorced from the text and the visitor can no longer easily locate places. She will usually just give up rather than click-and-load back-and-forth.

An integrated map, on the other hard, can be read from the article itself. This allows the visitor, as she reads thru the text, to locate the various unfamiliar placenames on the map and then go back to reading with a quick eye movement (and repeat down the page).

I am also a fan of Edward Tufte and I think it's important that maps (or any visual informative media) are clean and easily understandable, with little if any window dressing. This does not mean, however, that maps should be drab. Au contraire.

I use Inkscape to create my maps. I believe that SVG is the best format for maps, although the font support here in Wiki-land is poor (see discussion here).

The Baltic tribes, circa 1200 CE. The Eastern Balts are shown in brown hues while the Western Balts are shown in green. The boundaries are approximate.
-- > Latviešu
-- > Lietuvių
Commissioned by Renata3 and Xil.

Perhaps my best geographic map, showing the ancient Greek colonies on the north shore of the Black Sea.
Commissioned by Ghirlandajo.

This map shows the important cities, towns, and battle sites of the Swiss Peasant War. The light brown lines show the canton borders as they appeared in 1653. Instead of literally showing the Emmetal and Entlebuch valleys where the revolt began, I used the red starburst to highlight the area.
Commissioned by Lupo, who took this map and actually improved it (the nerve)! You can see his improved map here, as well as a very nice second map that he built using the 1st.

Italy in 1000 CE, part of my series of historical maps of Italy. This map may be too "busy".
This map was commissioned by Attilios

Italy and the eastern Adriatic in 1084 CE, part of my series of historical maps of Italy.

Here I used a gradient to show the Levant, hopefully implying the fuzziness of the definition. The genial NormanEinstein supplied the base map. Norman is among the best (or perhaps is the best) geographic mapmaker here in Wiki-land.

The routes travelled by the Christian armies in the disasterous Crusade of 1101

The following maps do not contain any labels. Such maps are useful under some circumstances, but the general geographic area must be recognizable to the average reader. The disadvantage, of course, is that these maps are less informative, but such maps can be useful in a multi-language encyclopedia.

The empire of Attila the Hun, circa 450 AD.

The Republic of Venice in 1796.

The domains of the Golden Horde in 1389 before the w:en:Tokhtamysh-Timur war, with modern international boundaries in light brown. The Principality of Moscow is shown as a dependency, in light yellow.

Duchy of Courland and Semigallia in 1740.

The Duchy of Naxos, also known as the Duchy of the Archipelago, in the year 1450.

Image:Danishmend 1097, locator map.svg‎|A map showing the lands of the Danishmends in 1097.